1. Field of the Invention
The invention relates to a double wire sternotomy suture apparatus and method for closing a split sternum employing optimal force in the process.
2. Description of Related Art
Sternotomy sutures are stainless steel sutures used to lace up the sternum after a surgery that requires cutting the length of the sternum to gain access to the chest cavity. A sternotomy is routinely performed when heart surgery is required. Sternotomy sutures are available from a number of companies such as the MYO/WIRE.RTM. suture available from A & E Medical Corporation, 5206 Asbury Road, Farmingdale, N.J. 07727.
In general, history has shown that sternotomy wires are the most safe and effective method for closing the sternum during the period of time necessary for the sternum halves to heal together. The wires are usually left implanted for life because they are atraumatic and removal could cause difficulties especially if bone has grown around the wire. Surgeons prefer the use of wires because they are simple to apply, produce the least post surgical complications, and are relatively inexpensive. The prior art methods, however, have presented some installation and post operative problems described below.
The first major problem is that band tightening by twisting wires together with a pair of pliers is an inexact method. The surgeon has to develop a very sensitive "feel" for how much torque he or she can apply to properly tighten the band without breaking the wire. Consequently, it is common for a great number of suture wires to break during installation. As a counter to this, new wires have been developed which are more resistant to breaking during band tightening. A wire break, however, generally requires the surgeon to undo all finished sutures and start the process all over again. For fear of breaking a wire, a surgeon will tend to under torque the suture resulting in less than optimal closure pressure on the sternal knit line. This can lead to dehiscence problems.
A second major prior art problem relates to the consequence of movement along the sternum knit line. For a number of reasons, many patients develop a chronic cough after surgery that places a heavy stress on the suture wire bands. Stress is even greater for heavy, large chested persons. This can cause the bands to loosen or break. The resulting dehiscence (movement along the sternum knit line) is very bad especially if infection sets in. This condition usually requires a completely new operation to replace and tighten new sternal suture wires along with aggressive antibody treatment for the resulting infection. A reasonable estimate is that dehiscence and/or sternal infection complications incur in 1.5 to 2.0% of all heart surgery patients. Hospitals estimate that the additional cost to treat each of these patients averages $20,000 per patient or $300,000 minimum cumulative cost to a hospital performing 1,000 heart operations a year. Hence, an improvement in sternal closure that reduces dehiscence could be very cost effective and desirable.
The prior art patent literature discloses a handful of loop type surgical devices for other purposes. Note, for example, U.S. Pat. No. 5,259,846 entitled LOOP THREADED COMBINED SURGICAL NEEDLE-SUTURE DEVICE. That disclosure describes incorporating two ends of a looped suture into a surgical needle to facilitate quick knotting and tying as may be needed during critical surgical procedures.
U.S. Pat. No. 3,762,418 entitled SURGICAL SUTURE discloses a double strand, but not looped, suture preferably having needles at both ends. This enables double suturing simultaneously in a single procedure.
U.S. Pat. No. 5,089,012 entitled SURGICAL SUTURE, IN PARTICULAR FOR STERNOTOMY CLOSURE, discloses a typical prior art single needle surgical suture incorporating a single monofilament portion.
U.S. Pat. No. 4,602,636 entitled SUTURE WIRE WITH INTEGRAL NEEDLE-LIKE TIP is of possible relevance for its teaching of a suture having an integrated needle tip therein attached to a single homogenous piece of wire.
U.S. Pat. No. 5,092,868 entitled APPARATUS FOR USE IN THE TREATMENT OF SPINAL DISORDERS teaches an endless loop of wire flattened to form two strands which are employed along with a T-shaped handle to attach a bracket to the spinal cord. It is noted, with interest, however, that the two portions of the strands are mechanically held next to each other and can be manipulated as a unit to guide it through a spinal opening.
U.S. Pat. No. 5,501,688 entitled SURGICAL DEVICE FOR MANIPULATING WIRE discloses a tool and method for tightening a single strand suture having loops at both ends.
Lastly, the following patents are all cited as describing the general state of the art and appear to be of lesser relevance to the disclosed invention: U.S. Pat. Nos. 4,201,215; 4,512,346; 4,535,764; 4,813,416; and, 4,901,721.
Insofar as understood, none of the disclosed prior art appears to teach, hint or suggest a loop suture suitable for enclosing a split sternum such that optimal force is applied. Moreover, none of the prior art appears to disclose a method and procedure for fastening a suture to itself at the optimal tension T.sub.crit when double cabling begins.
It was in the context of the foregoing that the present invention arose.